Warm up♥ 2 – 18 evens only.♥ This will be graded in 10

minutes.

2. 2.79

4. 27.93

6. 61.78

8. 138.4

10. 7.16

12. 309.4°

14.107 °

16.1.6 °

18.72.5 °

9.2 Tangents and SecantsTangents and

secants are LINES.

A tangent line intersects the circle at

exactly ONE point.

A secant line intersects the circle at exactly TWO points.

A little extra information

♥ The word tangent comes from the Latin word meaning to touch

♥ The word secant comes from the Latin word meaning to cut.

Important Theorems

• Tangent Theorem:– If a line is tangent to

a circle, then the line is perpendicular to a radius of the circle drawn to the point of tangency.

The line AB is tangent to circle C at B.

How could we prove that segment CB and line AB are perpendicular?

Converse of the Tangent Theorem

♥ Go waaaayyy back… how do we get a converse statement?

♥ What would be the Converse of the Tangent Theorem?

♥ If a line is perpendicular to a radius of a circle at its endpoint on the circle, then the line is tangent to the circle.

Radius and Chord Theorem

• A radius that is perpendicular to the chord of a circle bisects the chord.

QR = 3

What is the measure of RS?

XR = 7 and WR = 2

Find the missing measures of the remaining segments.

RZ =

RY =

XW =

WZ =

XZ =

7

7

6.7

6.7

13.4

Let’s Practice

I need 2 volunteers to hand out

whiteboards and markers.

Your assignment

♥Pg 577; 10-13, 19-26

♥Pg 846, Lesson 9.2, 1-6